Apparatus for the continuous casting of a large strand such as a bloom or a slab generally includes a mold assembly which is followed by a roller guide for the strand.
The mold assembly includes two pairs of plates which cooperate to define the mold cavity. One of the pairs of plates is clamped between the other.
Clamping is usually accomplished mechanically using tie-rods which are stressed by means of clamping nuts. In such an arrangement, the clamping nuts must be subjected to very high torques in order to achieve clamping forces of the required magnitudes. This makes the clamping operation a difficult one. Furthermore, at least two, and frequently more, tie-rods are provided at either end of the mold assembly. This results in a relatively complex design both as regards machining of the mold assembly and obtaining the correct stresses in the various tie-rods.
In addition to proper clamping, a prerequisite for successful continuous casting is precise alignment of the mold cavity relative to the roller guide. One known alignment technique involves placing the mold assembly on the mold table or support and then shifting the mold assembly until the mold cavity is correctly aligned with the roller guide. Since the alignment process, which is time-consuming, is carried out in the casting machine, this technique greatly reduces the availability of the machine for casting.
An arrangement which enables the availability of the casting machine to be increased consists of two or more locator pins on the mold table and flanges on the mold assembly having holes which receive the locator pins. This arrangement, however, poses a problem when the plates defining the mold cavity are machined to remove wear marks and other surface defects generated during use. Thus, the positions of the plate surfaces relative to the holes in the flanges are changed when material is removed during machining so that the mold cavity is no longer in alignment with the roller guide when the mold assembly is placed on the mold table.
The preceding problem is overcome by a technique for aligning the mold cavity off the casting machine in a mold preparation area. The mold assembly is here again provided with flanges having holes which receive locator pins on the mold table. However, the positions of the holes in the flanges are adjustable. A template is placed in the mold cavity such that a face of the template intimately contacts one of the surfaces bounding the mold cavity. The surface contacted by the template is that which is to be aligned with the lower track or run of the roller guide when the mold assembly is on the mold table. The template has a leg which passes over the upper edge of the mold assembly and is provided with openings corresponding to the holes in the flanges of the mold assembly. The openings are at a fixed distance from the face of the template in contact with the mold surface to be aligned with the lower track of the roller guide. This distance, in turn, is equal to the desired distance between the locator pins on the mold table and the position to be occupied by the mold surface which is to be in alignment with the lower roller guide track. The holes in the flanges are aligned with the openings in the template and, after removal of the template from the mold assembly, the latter is set on the mold table so that the holes in the flanges receive the locator pins. The mold cavity is now properly aligned without the need for performing any adjustments in the casting machine.
Although the last-described technique avoids the problems outlined above, it increases the complexity of the mold assembly. Furthermore, the template required for this technique constitutes an additional item to be stored and maintained in an area which is already crowded.